Synthesis and Characterization of (Cu, S) Co-doped SnO2 for Electrocatalytic Reduction of CO2 to Formate at Low Overpotential

A novel copper (Cu) and sulfur (S) co-doped SnO2 material prepared by a facile hydrothermal method is demonstrated as an efficient electrocatalyst for the reduction of CO2 to formate. The as-prepared SC10 holds rutile structure, whereas both Cu and S are doped well into the SnO2, in which S2- and Cu2+ replace O2- and Sn4+, respectively. The overpotential observed in CO2-saturated 0.5 M NaHCO3 solution is as low as 130 mV (vs. RHE) at -0.75 V (vs. Ag/AgCl) and the maximum current density also increases to 5.5 mA cm(-2) at -1.2 V, which is 7-times higher than pure SnO2. The catalyst is stable for more than 33 h and the Faradic efficiency of formate is 58.5%. The as-synthesized catalyst will open up a novel route for efficient reduction to formate and has a great potential for relieving the greenhouse effect.